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    1954 Oldsmobile 98 5.3L 4BL 8cyl

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    See Details

    A/C Expansion Valve

    Inspect/Test/Replace

    To replace a standard thermostatic expansion valve (TXV):

    • Place the ignition switch in the OFF position.
    • Disconnect the battery cable.
    • Purge the system of refrigerant; use the proper recovery equipment.
    • Remove the insulation tape from the remote bulb.
    • Loosen the clamp to free the remote bulb.
    • Disconnect the external equalizer, if the TXV is so equipped.
    • Remove the liquid line from the inlet of the TXV.
    • Remove and discard the O-ring, if equipped.
    • Inspect the inlet screen.

    If it's clogged:

    • Clean and replace the screen.
    • Install new O-rings on the liquid line fitting, if equipped.
    • Attach the liquid line to the TXV. Tighten to proper torque.
    • Reconnect the external equalizer tube, if equipped.
    • Position the remote bulb and secure it with a clamp.
    • Tape the remote bulb to prevent it from sensing ambient air.
    • Replace the access panels and any hardware previously removed.
    • Reconnect the battery.
    • Leak test, evacuate, and charge system with refrigerant.
    • Do a performance test if required.

    If it is not clogged:

    • Place the ignition switch in the OFF position. Disconnect the battery cable. Purge the system of refrigerant; use the proper recovery equipment.
    • Remove the evaporator inlet fitting from the outlet of the TXV.
    • Remove and discard the O-ring, if equipped.
    • Remove the holding clamp (if provided on the TXV) and carefully lift the TXV from the evaporator.
    • Carefully locate the new TXV in the evaporator.
    • Insert new O-ring(s) on evaporator inlet, if equipped.
    • Attach evaporator inlet to the TXV outlet. Tighten to proper torque.
    • Install new O-rings on the liquid line fitting, if equipped.
    • Attach the liquid line to the TXV. Tighten to proper torque.
    • Reconnect the external equalizer tube, if equipped.
    • Position the remote bulb and secure it with a clamp.
    • Tape the remote bulb to prevent it from sensing ambient air.
    • Replace the access panels and any hardware previously removed.
    • Reconnect the battery.
    • Leak test, evacuate, and charge system with refrigerant.
    • Do a performance test if required.

    To replace an H-thermostatic expansion valve:

    • Disconnect the wire connected to the pressure cut-out or pressure differential switch as applicable.
    • Remove the bolt from the line sealing plate found between the suction and liquid lines.
    • Carefully pull the plate from the H-valve.
    • Cover the line openings to prevent the intrusion of foreign matter.
    • Remove and discard the plate to the H-valve gasket.
    • Remove the two screws from the H-valve.
    • Remove the H-valve from the evaporator plate.
    • Remove and discard the H-valve to evaporator plate gasket.
    • Install a new H-valve with gasket.
    • Replace two screws. Torque to 170-230 in.-lb. (20-26N?m).
    • Replace the line plate to H-valve gasket.
    • Hold the line assembly in place and install the bolt. Torque to 170-230 in.-LB (20-26N?m).
    • Replace the access panels and any hardware previously removed.
    • Reconnect the battery.
    • Leak test, evacuate, and charge system with refrigerant.
    • Do a performance test if required.
    NOTE
    if the expansion valve requires replacement for any reason, replace the Receiver Dryer . it is right in front of the expansion valve and should have prevented the corrosion that ruined the expansion valve. the evaporator would fail next if the expansion valve was open.

    CAUTION
    Exercise extreme caution, and pay heed to every established safety practice when performing these or any automotive air-conditioning system service procedures.

    Cleaning the thermostatic expansion valve:

    1. Remove the diaphragm, the capillary, and the remote bulb assembly.
    2. Remove the superheat adjusting screw. Count the number of turns required to remove the screw. Knowing the number of turn aids in relocating the proper position when reassembling the valve.
    3. Remove the superheat spring and the valve seat. Remove the valve and push rod(s).
    4. Clean the valve and all parts in clean mineral spirits. Let the parts drain and then blow them dry.
    5. Reverse Steps 1-4 and reassemble the valve.
    6. Check the expansion valve for maximum and minimum flow as outlined in this procedure.
    7. If the valve fails to pass the maximum/minimum flow test, then attempt to adjust the superheat spring setting.
    8. If the valve fails the test repeatedly, a new valve must be installed. No further repair is possible.

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